1. Field of the Invention
The technical field of the present invention relates to a semiconductor device. Here, semiconductor devices refer to general elements and devices which function utilizing semiconductor characteristics.
2. Description of the Related Art
Attention has been focused on a technique for forming a transistor using a semiconductor thin film formed over a substrate having an insulating surface. The transistor is applied to a wide range of electronic devices such as an integrated circuit (IC). A silicon-based semiconductor material is widely known as a material for a semiconductor thin film applicable to a transistor. As another material, an oxide semiconductor has been attracting attention.
For example, a transistor including a semiconductor thin film formed using an amorphous oxide containing indium (In), gallium (Ga), and zinc (Zn) (In—Ga—Zn—O-based amorphous oxide) is disclosed (see Patent Document 1).